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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 6 |
| 3 | 1818 |
| 4 | 1130256 |
| 5 | 3451956516 |
| 6 | 21241004664348 |
| 7 | 332469512259607296 |
| 8 | 9510929074212911717760 |
| 9 | 521875340203828179569609700 |
| 10 | 47602100904962622927705491352020 |
| 11 | 7181861163349151796773697873026037828 |
[1,6,1818,1130256,3451956516,21241004664348, 332469512259607296,9510929074212911717760, 521875340203828179569609700, 47602100904962622927705491352020, 7181861163349151796773697873026037828] |